This invention relates to a rolling bearing unit that supports an automobile wheel and a disk of a disk brake so that they rotate freely with respect to the suspension, as well as supports a caliper or support of the disk brake, and relates to the manufacturing method thereof.
The wheel of an automobile, and the disk of a disk brake are supported by a rolling bearing unit for wheel support on the knuckle of a suspension so that they can rotate freely. On the other hand, the caliper or support of the disk brake is generally fastened to and supported by the knuckle. However, from the aspect of improving assemblibility of the caliper or support in an automobile or improving the handleability of the caliper or support, in recent years, fastening and supporting the caliper or support to a member on the stationary side of the wheel-supporting rolling bearing unit has been considered. For example, construction in which a flange for fastening to and supporting the caliper or support is located on the outer peripheral surface of the outer race, which is the stationary side member of the wheel-supporting rolling bearing unit, is disclosed in US Patent Application Publication No. 2003/0165280.
FIG. 16 and FIG. 17 show an example of a wheel-supporting rolling bearing unit having a flange on the outer peripheral surface of the stationary side member for fastening to and supporting the caliper or support that differs from the construction that is publicly disclosed in US Patent Application Publication No. 2003/0165280, and was previously considered by the inventors. This wheel-supporting rolling bearing unit comprises: an outer race 1 that is a stationary side member, a hub 2 that is a rotating side member, and a plurality of balls 3 that are rolling bodies. Of these, the outer race 1 has a double row of outer raceways 4a, 4b formed around an inner peripheral surface thereof. Also, on a section toward the inside end of the outer peripheral surface, there is a connection flange 5 for connecting and fastening to the knuckle (not shown) and similarly, in a section in the circumferential direction of the middle section (section adjacent on the outside in the axial direction of the connection flange 5) there is a stationary side support flange 6 for supporting and fastening to the caliper or support (not shown). Here, ‘inside’ in the axial direction refers to the center side in the width direction of the vehicle when assembled in the vehicle, and is the right side in FIGS. 8, 12, and 16 to 18, is the bottom side in FIGS. 1 to 7, 9 to 11, 13 and 15, and is the top side in FIG. 14. On the other hand, the ‘outside’ in the axial direction, refers to the outside in the width direction of the vehicle, and is the left side in FIGS. 8, 12, and 16 to 18, the top side in FIGS. 1 to 7, 9 to 11, 13 and 15, and the bottom side in FIG. 14.
Also, the hub 2 comprises a main hub body 7 and an inner race 8 that is fitted and fastened onto the inside end of the main hub body 7. This kind of hub 2 has a rotating side support flange 10 located on the outer peripheral surface of the section toward the outside end thereof for fastening to and supporting the wheel and disk 9 (see FIG. 18 to be described later), and a double row of inner raceways 11a, 11b that are similarly located around the middle section and inside end section. Of these, the rotating side support flange 10 and the inner raceway 11a on the outside are formed around the outer peripheral surface of the main hub body 7, and the inner raceway 11b on the inside is formed around the outer peripheral surface of the inner race 8. Moreover, press-fit through holes 12 that penetrate through in the axial direction are formed at a plurality of locations in the circumferential direction of the rotating side support flange 10, and studs 13 are press-fitted and fastened to the inside of each of these press-fit through holes 12. Also, a plurality of balls 3 are located between each of the outer raceways 4a, 4b and each of the inner raceways 11a, 11b so that they can roll freely. In the example shown in the figures, balls 3 are used as the rolling bodies, however, in the case of a rolling bearing unit for a heavy automobile, tapered rollers may be used as the rolling bodies.
When the wheel-supporting rolling bearing unit constructed as described above is installed in an automobile, the inside surface of the connection flange 5 is brought into contact with the side surface of the knuckle, and this connection flange 5 is connected and fastened to the knuckle. Also, as shown in FIG. 18, the section toward the inner radial side on the surface of one side of the disk 9 is brought into contact with the rotating side installation surface 14, which is the outside surface of the rotating side support flange 10, and the disk 9 and wheel are fastened to and supported by this rotating side support flange 10 by a plurality of studs 13 and nuts (not shown). Moreover, in the case where the disk brake is a floating caliper disk brake, the support that supports the caliper is brought into contact with and installed on the stationary side installation surface 15, which is the outside surface of the stationary side support flange 6, and in the case where the disk brake is an opposed piston disk brake, the caliper is brought into contact with and installed on the stationary side installation surface 15. Also, the disk brake is formed by combining the disk 9 and caliper. When braking, a pair of pads that are installed on the support or caliper on both sides of the disk press against both side surfaces of the disk. The wheel-supporting rolling bearing unit that is shown in the figures is for driven wheels (rear wheels in a FF vehicle, and front wheels in a FR vehicle), however, in the case of a wheel-supporting rolling bearing unit for drive wheels (front wheels in a FF vehicle, rear wheels in a FR vehicle, and all wheels in a 4WD vehicle), a spline hole is formed in the center section of the hub. When installing the rolling bearing unit in the automobile, the spline shaft (drive shaft) of a constant velocity joint is connected by a spline connection with the spline hole.
However, when manufacturing a wheel-supporting rolling bearing unit that has a stationary side support flange 6 as described above, and that is used in combination with the disk 9, conventionally, the finishing process of the stationary side installation surface 15 and the finishing process of the rotating side installation surface 14 were performed separately and independently (there was no direct relationship between the processes). The same is true for the finishing process of the stationary side installation surface 15 and finishing process of the pair of parallel braking friction surfaces 16, which are both of the side surfaces of the outer half in the radial direction of the disk 9. However, by performing the finishing process of the stationary side installation surface 15 and the finishing process of the rotating side installation surface 14 or both braking friction surfaces 16 separately and independently, even though the surface precision (for example, flatness, or squareness with respect to the center axis) of these surfaces 14, 15 and 16 can be adequately maintained, there is a possibility that after completion it will not be possible to adequately maintain the relative precision (for example, parallelism) between these surfaces 14, 15, 16.
For example, when the parallelism between the rotating side and stationary side installation surfaces 14, 15, or the parallelism between the stationary installation surface 15 and both braking friction surfaces 16 is not adequately maintained, it is not possible to obtain a good (desired) positional relationship between both braking friction surfaces 16 and the support or caliper that is installed on the stationary side installation surface 15. As a result, the contact state between both braking friction surfaces 16 and the aforementioned pads becomes nonuniform. Also, as this nonuniform level becomes large, it becomes easy for vibration with noise, or in other words judder, occurring during braking. Therefore, in order to suppress the occurrence of this kind of judder, a manufacturing method is preferred in which it is possible to adequately maintain the parallelism between the rotating side installation surface and stationary side installation surface 14, 15, and between the stationary side installation surface 15 and both braking friction surfaces 16.
Other prior art that is related to the present invention is the manufacturing method for a wheel-supporting rolling bearing unit that is disclosed in Japanese Translation Publication of PCT International Application No. 2003-514680. The manufacturing method disclosed in this publication is a method in which after assembling the stationary side member, rotating side member and the plurality of rolling bodies of the wheel-supporting rolling bearing unit, a turning process, which is a flat surface processing, is performed on the rotating side installation surface, which is the surface on which the disk is installed, while rotating the rotating side members with respect to the stationary side members. By using this kind of method, it is possible to suppress run out in the axial direction of the rotating side installation surface when rotating, so it is possible to suppress the occurrence of judder due to run out in the axial direction of the disk that is installed on this rotating side installation surface. However, in this publication, a wheel-supporting rolling bearing unit comprising a stationary side support flange for fastening to and supporting a caliper or support is not disclosed as the object of the invention. In other words, the object of the manufacturing method that is disclosed in this publication is not the manufacture of a wheel-supporting rolling bearing that comprises the aforementioned stationary side support flange, and it is not the intent of the this manufacturing method to maintain the parallelism between the stationary side installation surface, which is the side surface of this stationary side support flange, and the rotating side installation surface or the braking friction surfaces of the disk.
Also, in U.S. Pat. No. 6,158,124, a manufacturing method is disclosed for a wheel-supporting rolling bearing unit in which after assembling the stationary side member, rotating side member, plurality of rolling bodies and the disk of the wheel-supporting rolling bearing unit, a turning process, or in other words, a flat surface processing is performed on the pair of braking friction surfaces of the disk while rotating the rotating side members and disk with respect to the stationary side members. By employing this kind of manufacturing method, it is possible to suppress run out in the axial direction during rotation of the braking friction surfaces, and thus it is possible to suppress the occurrence of judder due to run out in the axial direction. However, even in U.S. Pat. No. 6,158,124, the manufacture of a wheel-supporting rolling bearing unit that comprises a stationary side support flange for fastening to and supporting the caliper or support is not disclosed as the object of manufacturing. In other words, as in the case of the manufacturing method disclosed in Japanese Translation Publication of PCT International Application No. 2003-514680, the object of the manufacturing method that is disclosed in U.S. Pat. No. 6,158,124 is not the manufacture of a wheel-supporting rolling bearing that comprises the aforementioned stationary side support flange, and it is not the intent of the this manufacturing method to maintain the parallelism between the installation surface, which is the side surface of this stationary side support flange, and the pair of braking friction surfaces.